Since the 1950's and the initial invention of the hearing aid t-coil for use in receiving electromagnetic audio signals from telephones with electromagnetic voice coils, improvements have been continuously sought. This alternative to the hearing aid microphone input avoids the feedback problems of the acoustic loop associated with speakers and microphones. Later when voice coils shrank to reduce power for cordless and wireless phones, auxiliary coils were added to speaker assemblies to enhance the electromagnetic fields and volume controls were added to claim the label of “hearing aid compatible” (HAC) phones.
Since these early days, the environment has changed, rapidly going from wired phones to cordless to wireless and to other methods of utilizing telecommunications devices such as phone integrated personal digital assistants, computers with voice and data capabilities, entertainment devices with headsets as well as short range radios evolving from the citizens band system. Many of these recent and advanced devices have to be synchronized to communicate in regard to data transfer and many transmit and check protocols for data transmission. In the realm of the audible, people with hearing aids and cochlear implants are finding difficulties in accessing the Internet as well as participating in day to day communications over the growing list of electronic communication devices. Many of these devices are not compatible with the needs of the hearing impaired. The electronic noise emitted from the circuitry of most of these devices creates electronic interference and results in acoustic noise in hearing aids and cochlear implants. Many of these devices fall short of meeting regulatory criteria for electromagnetic devices. This occurs where they are creating noise in the environment affecting other electronic equipment as well as adversely affecting the hearing impaired. Many hearing aid users simply remove their hearing aids and turn up any volume control to listen on phones or headsets and try to make the best of it. Inventions that simply turn up the volume are not very effective because hearing loss is usually frequency dependent. Hearing aids are necessary and they can compensate for loss at a given frequency, helping balance the hearing profile so that volume is more effective and some frequencies are not over driven so others can be heard.
There are many aspects against which to evaluate devices that are going to be more helpful to the hearing impaired in communicating with these recent and advanced devices and yet there are other aspects that can facilitate communication between devices utilizing the similar attributes of this invention. The following prior art is evaluated against the following specific aspects of this invention. These aspects are: the location and mounting environments and arrangements of the transducer, the transducer structure, content, field shape and intensity, power consumption, signal characteristics, noise reduction, and requirements of adjacent items.
Prior art most representative of attempts to assist the hearing impaired are U.S. Pat. No. 5,796,821 to Crouch “Hearing Aid Telephone Interconnect System” (1999), U.S. Pat. No. 6,320,959 to Crouch (2001) “Hearing Aid Telephone Interconnect System” and U.S. Pat. No. 6,438,245 to Taenzer (2002) “Hearing Aid Communication Earpiece” disclose similar approaches. U.S. Pat. Nos. 5,796,821 and 6,320,959 are essentially the same patent with some minor claims added to the second patent. The basic disclosure is the simultaneous routing via a cable connection of a telephone audio signal to a separate earpiece hooked over the ear and contacting a behind the ear hearing aid and the conventional handset. The earpiece contains an open air looped coil that electromagnetically couples with a t-coil mounted inside the behind the ear hearing aid. Through this coupling the audio signal is transferred and the hearing aid switch is set to t-coil allowing the signal to be transferred to the hearing aid amplifier. This avoids feedback since the microphone is out of the acoustic loop and allows the hearing aid volume to be turned up fully. However, the extra cord and earpiece are additional burdens for the hearing impaired to handle and to keep from getting tangled with other cords. Essentially this open air loop is large and serves the same function as the auxiliary coil added to the old voice coil speakers in the handsets to achieve a classification of “hearing aid compatible”. U.S. Pat. No. 6,438,245 also discloses an additional earpiece mounted to the hearing aid but with the addition of an acoustic tube from the earpiece out to the microphone of the hearing aid. The earpiece also contains a transmitting coil to couple to a t-coil. The earpiece also has two-way wireless communication capabilities. However, this design still has the burden of an additional item and complexity of mounting it and removing it from the hearing aid.
U.S. Patent Application 20010055386 “Method and Apparatus for a Hearing Aid Coupler System” adds a new aspect to the coupling in that it is back in the handset where no additional cables or attachments are required. The coil is designed to be mounted in the handset above the speaker in the preferred embodiment with the center line of the toroid coil design parallel to the face of the handset earpiece. However, the highest field intensity for the toroid coil is in the center of the coil. Tests have indicated that the coil acting by itself is inferior in performance to conventional speakers with the auxiliary coil. Therefore, the toroid coil is misaligned in the configuration and not in intimate proximity of the hearing aid t-coil further reducing its effectiveness.
U.S. Pat. No. 5,615,229 to Sharma (1997) “Short Range Inductively Coupled Communication System Employing Time Variant Modulation” also utilizes the t-coil in a hearing aid. However, the transmitting coil to the t-coil is a large neck-worn inductive loop that is driven by an amplified signal. Although claims are made to smaller loops, the preferred embodiment is an open air loop requiring extra apparatus and cables. A claim is also made of adding a ferrite core but it is left to assume an axial configuration which essentially is a toroid but the essential implementation is assumed to still require a separate item with cabling, thus creating excessive equipment. Further the signal(s) delivered to the inductive loops are amplified and require considerable circuitry to process the signal to the inductive loop. Although noise susceptible baseband is avoided with the time variant RF signal, processing the baseband signal is reverted to in transmitting from the inductive loop to the t-coil.
U.S. Pat. No. 6,381,308 to Cargo (2002), U.S. Pat. No. 4,361,733 to Marutake (1982), U.S. Pat. No. 4,908,869 to Lederman (1990), U.S. Pat. No. 6,516,075 to Jacobs (2003) U.S. Pat. No. 5,276,910 to Buchele (1994) all utilize the large inductive loop coil or a similar configuration, also referred to as antenna, in one form or another or derivatives thereof to transmit to the hearing aid t-coil. Some loops are tied to a location in the room versus being attached to the body. Use of a large loop requires amplification circuitry and if the loop is located in the room, the effectiveness is limited to that immediate area. All these devices require an additional item separate from the source signal device such as a phone (wired, cordless or wireless), or entertainment headset. The loop is large, requires connections and transmits amplified electromagnetic fields in all directions in the immediate environment.
U.S. Pat. No. 5,086,464 to Groppe (1992) “Telephone Headset for the Hearing Impaired” does not require a hearing aid but uses a headset in which to apply an audio signal from a phone through its own microphone or an audio signal through its own built in t-coil to receive electromagnetic field inputs from the voice coil in the speaker. This design was perceptive in recognizing the need for separate volume and tone controls for each ear, since the compensation of a hearing aid is not part of this design. However, this again is a separate and bulky device that must be carried and utilized separate from the signal source, a phone. If the quality of the signal varies with the use of different phones, adjustments to volume must be made to each ear piece.
U.S. Pat. No. 5,042,084 Daly (1991) and U.S. Pat. No. 5,069,210 to Juetter (1991) disclose methods to transmit audio signals to implanted receiving transducers requiring the involvement of sophisticated circuitry in doing this. U.S. Pat. No. 5,042,084 utilizes an inductive coil to receive both audio and RF input. The RF transmitting coil requires close alignment of its coil core to the receiving coil core to avoid signal detuning. U.S. Pat. No. 5,069,210 also uses an RF scheme to transmit an RF signal to the implanted receiver. Both disclosures require implanted circuitry to decode the RF signals back to simulate a normal audio signal that gets translated into the acoustic equivalent of what the ear nerve interface requires. The additional signal processing and associated circuitry increases the cost and the size of the implant. Many newer cochlear implants are including a small t-coil that directly supports electromagnetic transmission of audio signal from a sending transducer to the t-coil from which the different frequencies are derived.
Besides audio signal transmission for purposes of supplying an audible signal, other signal types may be transmitted through such means at a rapid rate for the purpose of logic data transfer or exchange between devices without the restrictions of cables. U.S. Pat. No. 4,864,633 to Chatelot (1989) discloses a means to accomplish this by using a tuned transmitting-receiving coil to inductively couple with a movable receiving and transmitting coil. Through this arrangement a high rate data exchange can occur. However, the size of the coils and the circuitry required would be prohibitive in today's wireless technology and mobile environment. Reduction in size would weaken the signal significantly in attempts to miniaturize, which leads to signal to noise ratio problems.
Another disclosure that focuses on voice and data transmission is in U.S. Pat. No. 4,584,707 to Goldberg (1986) wherein transmission and reception is accomplished through magnetic lines of induction from a base station and at least one mobile station. Voice is transmitted at one frequency and data at a higher frequency. The induction coupling is through antenna versus coils. The antenna are worn by the person as the mobile unit and are again large and operate at radio frequencies which require circuit processing in the receivers to get the data and voice back into usable form leading to complexity and costs.
U.S. Pat. No. 5,293,400 to Monod (1994) uses the inductive principle to interconnect sections of a data bus. The inductive transducer is a flat spiral winding (having no core) that is printed on a circuit board and the transmitter is aligned to a receiver on a parallel and adjacent printed circuit board with the alignment on the centerlines of the two flat spiral windings. Each spiral winding alternates function from transmitting to receiving as required. Data flow rates on an RS 232 bus have achieved data flow rates of 300 kbits/s. However, the intent here is to fix these inductors relative to each other and the spirals are relatively large at about a 2 inch diameter. The size, printed circuit implementation and the flat nature make this embodiment fragile for movable devices that need to interconnect versus fixed bus sections on printed circuit boards.
U.S. Pat. No. 5,084,864 to Turnbull (1992) relates another version of inductive transmission for the purpose of communicating information. This discloses the use of RF signals from a base station forming a network over balanced transmission lines (2) with a plurality of remote units comprised of U-shaped couplers in proximity over the transmission lines and connected to RF receivers or senders such that they can communicate over this network. These U-shaped couplers are positioned flat and parallel to the transmission lines. The U shaped couplers were formed of a thin flat bare piece of metal, each leg being parallel to the two transmission lines and connected to RF senders or receivers. Of course this embodiment is not mobile and has to remain adjacent to wherever the transmission lines are placed. The couplers are made for RF usage and not direct signal transmission and for transfer of data limited to devices that are positioned along the transmission lines.